In my humble opinion, Warhammer 40k has the best setting in the games business. I simply love the mixture of futuristic and medieval theme! One of the iconic elements of this world are the purity seals, prayer of victory or protection borne by all kind of Imperial troops.

For my Techpriest cosplay, I wanted to make some of of them. I tried various approach, and found one that for works for making tons of realistic, resistant and highly detailed purity seals... under $1 each!

Are you ready? First of all praise the Omnissiah, father of all technology!

Step 1: Materials

You'll need:

Lot of hot glue, a camping hotplate, acrylic colors, a disposable metal bowl, grease, aluminum foil.

A mold. There are a number of ways how you can obtain it; in the final version I've made it with a 3D printer due to the high level of detail of the seal I wanted, but for example in the first experiments a simple engraved potato performed very well!

Some pieces of white fabric, sheets of transfer paper, an iron

Here are the 3D models I've used for the mold:

Imperial skull: https://tinkercad.com/things/l9zI1TjJAO3

Omnissiah: https://tinkercad.com/things/gC65pRS4JB2

If you need to have the model printed, incidentally I happen to know a good 3D hub (xD):

https://www.3dhubs.com/lugano/hubs/loskana-0

Step 2: The Ultra Secret Ingredient

Yep, the core of this revolutionary production method lies in the humble hot glue!

When it has been molded, it has actually some very, very nice properties:

Resistant but not fragile: For breaking one of my seals you actually need a lot of effort!

Scratch/smudge resistance: when it's heated the hot glue will nicely mix with the acrylic, making the whole seal, exterior and interior, of the same color!
Cheap and easily obtained: you can find hot glue in almost every hardware store, and I was able to purchase 1 kg of hot glue sticks for ~12 €.

100% reusable: if you don't like a seal you can simply re-melt it!

Now turn your hotplate and put on it a disposable metal bowl. I found mine in a cheap store as cookware... I would never actually drink from them, but for this project they were fantastic! Note that you will need one of them for each color you're planning, as it can be difficult to clean them afterwards.

Put the desired amount of hot glue on the bowl, and let it meld. I usually cut the sticks just to ease the process. You should experiment the right temperature to keep; usually if you see smoke coming from the glue it's too hot ;)

When the hot glue is completely melted, add your acrylic paint. I found the best results with fluid acrylic, even with a very basic quality! I bought mine from a kid store.

When the hot glue is hot enough, it's best to take if off from the hotplate, and simply use a candle to keep it melted.

Step 3: Hot Glue Molding

Now that the hot glue is almost ready, take your mold and apply a thin layer of grease. I've used a leather care grease, but I think that anything similar to petroleum jelly will work here. The goal is very simple, to prevent the hot glue sticking to the mould. Don't worry to put too much, as some little imperfection on the seal will increase its realism.

Remember to put the grease at each use! Also put some on the aluminium foil.

Now comes the magic. Pour some melted hot glue on the aluminium foil, and wait ~30/60 second for the hot glue to slightly cool off (experiment a little for better results). Now press your mold, and wait for it to completely cool down.

Gently start to peel it off from the aluminium foil; if you find that the hot glue still stick, wait a little longer. Be patient, work from all the angles, and it will eventually separate from the foil. Do the same with the mold, remember to be gentle!

Notice how the hot glue gives that nice jagged ring around the seal, just like real wax, no one identical to another? Also some little imperfection here and there just add for a realistic look!

Step 4: Rinse and Repeat

The production process takes ~5 min of time for each seal. With two molds and approximately 200 gr. of hot glue (~2.4 €), in half an hour of work I've made... 16 seals. More than enough to literally fill a costume of awesomess!

Notice that my goal was to make seals with the Mechanicus symbol, that is by far the most damn complicated in all the 40k universe xD If it worked for me with that level of details, I'm sure it will work also for your chosen symbol!

Step 5: And Now the Parchment

Now that the main seal is done, we'll prepare the fabric.

Choose the text you want to print. I suggest lexicanum (http://wh40k.lexicanum.com/wiki/Portal:Quotes) for ideas of the content; use an image editor like Gimp to prepare the image, with an heavy Gothic font (I've used Squelar, I simply love it). I've employed a simple combination of black text on a white fabric, but you're free to experiment with other colors, too.

A purity seal is after all part of a warrior's armor, and I believe that only a coward warrior would bear an immaculate armor. A little touch of washed-up always improve the credibility of a cosplay. For that, I've applied some image filter to slightly ruin the image.

In this image you'll find an example of prayer I've printed.

With the same principle, we'll now stain the fabric paper to represent years of gruesome wars in blood and mug. First of all, pour some coffee in a glass of water and put it on the paper, for giving an uniform stained effect. Now pour some raw coffee on some spots, and leave it dry overnight.

The water will dry from the paper, and in the spots where you left more coffee the stain will be more visible!

Step 6: Final Touches

Follow the instructions in your transfer paper for properly applying it to the fabric. In my case it was simple as ironing it for ~30 seconds over the fabric. The heat transfer also helps fixing the stained colour, making it water-resistant.

For some final touches, cut some little pieces around and burn the edges with a candle.

You're almost done!